This application is a division of my copending patent application Ser. No. 735,311 filed May 20, 1985, entitled Injection Method and Apparatus with Electrical Blood Absorbing Stimulation, a continuation-in-part of my copending patent application Ser. No. 638,695 filed July 19, 1984 entitled Method and Apparatus for Initiating Reperfusion Treatment by an Unattended Individual Undergoing Heart Attack Symptoms, now U.S. Pat. No. 4,658,830, and a continuation-in-part of my copending patent application Ser. No. 708,845 filed Mar. 6, 1985 entitled t-PA Composition Capable of Being Absorbed into the Blood, now U.S. Pat. No 4,661,469.
This invention relates to the treatment of patients by medicament injection and more particularly to medicament injection treatment under circumstances where intravenous injection is not practical but the fast response time of an intravenous injection is desirable.
One set of circumstances where these conditions are presented is in initiating reperfusion treatment by an unattended individual undergoing heart attack symptoms.
When a clot forms in a blood vessel, the body organ being supplied with blood by that blood vessel is compromised or totally deprived of blood supply. Depending on the blood vessel in which this occurs, the threat to the life of the individual is either small or very great as in the circumstances to be addressed by the material below, i.e. certain life threatening circumstances. Clot formation in a vessel is described as thrombosis. Substances which dissolve thrombi are called thrombolytic substances. When a coronary artery clot is dissolved, the resultant establishment of blood flow to the heart is called reperfusion.
Examples of life threatening clot formation in arterial vessels are cerebral thrombosis, renal thrombosis, ophthalmic artery thrombosis, and very importantly, thrombosis of a coronary artery. In approximately 85% to 90% of cases of acute myocardial infarction (coronary heart attack), a thrombus is found in the coronary artery preventing blood from flowing to the heart muscle (myocardium) and supplying it with essential oxygen and other nutrients. A consequence of a thrombus or clot forming in a coronary artery is the danger to the myocardium (heart muscle tissue that does the pumping of blood). Heart muscle deprived of its blood supply does not die immediately but does begin the process of becoming dead. The extent of the damage which is done to the heart muscle is, therefore, a function of the time during which the supply of blood to the infarct zone is restricted by the clot or occlusion.
Heretofore, the procedures undertaken to actually establish reperfusion to the infarct zone have always been undertaken in a hospital environment or equivalent. The so-called "pre-hospital" treatment was, in general, directed toward keeping the patient alive and getting the patient into the hospital environment as soon as possible so that treatment minimizing the heart muscle damage could be accomplished.
The treatment undertaken in the hospital environment involves certain procedures for establishing reperfusion in the infarct zone of the patient's heart. Where immediate surgery was not clearly indicated, the establishment of reperfusion was accomplished by procedures which had the effect of unblocking the occlusion. The available procedures included mechanical catheterization and the administration of thrombolytic agents. Known thrombolytic agents, such as streptokinase or urokinase required intercoronary infusion or the slow infeed of the agent within the vessel at the site of occlusion by means of a catheter. In recent years, intravenous infusion of streptokinase has been shown to be effective.
More recently a substance called tissuetype plasminogen activator or t-PA has been utilized experimentally. (The New England Journal Of Medicine, Mar. 8, 1984, Vol. 310, No. 10, pp. 609-613) Unlike other plasminogen activators, such as streptokinase or urokinase, t-PA--which is found in only small amounts in the body--acts specifically on clots and not on other proteins in the blood, when maintained at appropriate and effective levels.
A 1984 Commentary found in Biochemical Pharmacology Vol. 33, No. 12, pp. 1831-1838 entitled "Coronary Thrombolysis: Pharmacological Considerations with Emphasis on Tissue-Type Plasminogen Activator (t-PA)" contains the following conclusionary statement:
"Selection of pharmacological agents for induction of coronary thrombolysis has been determined largely by availability. Unfortunately, both streptokinase and urokinase induce a systemic lytic state with depletion of circulating fibrinogen plasminogen, and .sub.2 - antiplasmin, and accumulation of fibrin degradation products. All of these factors conspire to set the stage for hemorrhage with a risk of serious bleeding. Intravenous administration of these agents is limited by a lower success rate, in part because the upper bound of dose is constrained by the risk of inducing a severe systemic lytic state. PA0 The probability that progress in recombinant DNA technology will lead to widespread availability of tissue-type plasminogen activator is particularly exciting because of the clot specific properties of t-PA. For coronary thrombolysis its potential advantages include: safety and efficacy of intravenous administration of high doses; effective clot lysis without induction of a systemic lytic state; prompt implementation without the need for extensive characterization of the coagulation and fibrinolytic systems in each patient prior to and during therapy; avoidance of frank allergic reactions or variations in dose-response relation due to immune complex formation; ease of minute-by-minute adjustment of dosage and prompt termination of fibrinolysis when needed because of the short biological half-life of t-PA and the lack of induction of a systemic lytic state."
The promise attributable to t-PA administration was discussed at a news conference at a meeting of the American Heart Association and reported by the New York Times on Nov. 16, 1983, in an article entitled, "Protein of Cancer Cells Used to Halt Coronaries." The article refers to injection of t-PA by stating the following: "The protein [t-PA]can simply be injected into the vein in the arm of the patient seized by a myocardial infarction or heart attack, and it travels through the blood to dissolve a clot, in much the same way as Draino clears up stopped plumbing."
The article further indicated under the sub-heading "Hopes for Future Application" that many physicians have expressed excitement about research into the use of t-PA to treat heart attacks because they hope that some day it may be used in emergency rooms and ambulances to stop heart attacks at their earliest stages before they kill or cause permanent damage. Under the "Hopes for Future Application" sub-heading there is also included the following paragraph: "Dr. Burton E. Sobel of Washington University, one of the researchers, speculated that patients might some day carry a vial with them so that the drug could be injected immediately after they felt chest pain and other early symptoms of a heart attack."
In medical parlance, a vial is a container for a quantity of liquid medicine or diluent having a rubber stopper capable of being pierced by a hypodermic needle of a syringe to enable the operator of the syringe to withdraw a predetermined dosage of the liquid from the vial. In the case of t-PA, the dosage could then be injected into the mother liquid container of an infusion assembly. The necessity to administer the drug by slow intravenous infusion or by slow intravenous injection presents a significant barrier to self-administration from a practical view point, particularly when considering the disconcerting circumstances of the individual undergoing the symptoms of a myocardial infaction.
The development of a effective self-administration procedure for t-PA sufficient to enable its utilization by a targeted coronary prone individual immediately following onset of symptoms, would materially increase the potential efficacy of t-PA as a thrombolytic agent by insuring its use at the earliest possible time often before irreversible heart muscle damage has occurred, and, at the same time, provide a treatment of the pre-hospital or pre-ambulance type which for the first time is directly effective to minimize heart muscle damage accompanying myocardial infarction.
With respect to t-PA, a severe threshold question is presented as to whether an intravenous injection would be effective. Even though t-PA may be regarded as a clot selective thrombolytic agent, when introduced into the blood stream at a predetermined level, tests thus far performed show that the concentration can be increased to the point that a systemic lytic state can be induced. Intramuscular injection involves the introduction of a concentrated dosage of t-PA in an area contiguous to and substantially surrounding the wound caused by the penetration and withdrawal of the injection of the hypodermic needle. Consequently, it would be expected that at least a localized lytic state would be induced resulting in hemorrhage from the needle wound. Unexpectedly, tests have shown that no such hemorrhage does in fact occur.
Beyond this threshold question, exists the question of whether sufficient quantities of the t-PA injected into the muscle tissue would be absorbed in time to be effective. t-PA is a large protein. It would not be exected that it would be absorbed into the blood stream in discernible quantities. Extra-vascular levels of protein are about 1/10 that of intravascular protein. It is thought that this is so because the capillary pores through which transport of protein can occur are small relative to the molecular size of protein and limit protein transport because of electrical charge. It was thus highly problematical as to whether a large protein such as t-PA, when given intramuscularly, i.e. outside the blood vessels, would find its way rapidly into the blood stream in discernible quantities. Applicant tests have shown that unexpectedly t-PA does find its way rapidly into the blood stream in discernible quantities after intramuscular injection.
In accordance with the principles of the present invention, enhancement of blood absorption of t-PA may be accomplished in two ways. First, by injecting a blood absorption enhancing agent, such as hydroxylamine hydrochloride, into the muscle tissue along with the t-PA and second, by applying blood absorption enhancing electrical stimulating cycles. Moreover, in order to provide for total treatment it is within the contemplation of the present invention to also inject into the muscle tissue with the t-PA a anti-arrhythmic agent, such as lidocaine, an anti-reclotting agent, which may be either a thromboxane synthetase inhibitor, such as dazoxiben, or an antagonist for the receptor of thromboxane A, such as SQ 27,427 and a reperfusion damage preventing agent, such as superoxide dismutase (SOD) or S-aminotrimethyleneaminoethyl thiophosphate.
In accordance with the principles of the present invention this objective is accomplished by injecting a dosage of the liquid medicament into the muscle tissue of the patient and applying to the patient who has received the injection repeated blood flow stimulating cycles, each of which includes a period of electrical stimulus during which the muscle tissue which received the liquid medicament tenses followed by a period of no electrical stimulus during which the muscle tissue which received the liquid medicament is allowed to relax inducing enhanced blood flow within the muscle tissue and continuing the application of the repeated blood flow stimulating cycles until the injected medicament has been sufficiently absorbed into the blood to achieve patient response.
An object of the present invention is the provision of apparatus for effecting the aforesaid treatment method. Preferably, the injecting means of the apparatus constitutes an automatic injector of the type including a stressed spring releasable by a releasing mechanism actuated in response to the accomplishment of a predetermined muscle actuating procedure. Preferably, the electrical blood flow enhancing cycle applying means includes a pair of electrode elements capable of being operatively applied to the patient through which an electrical circuit is completed so as to directly stimulate the muscle tissue receiving the injection or to stimulate the nerves controlling the muscle tissue receiving the injection so that the aforesaid blood flow stimulating cycles can be repeated.
Another object of the present invention is the provision of an apparatus of the type described which is simple in construction, effective in operation and economical to manufacture.
These and other objects of the present invention will become more apparent during the course of the following detailed description and appended claims.
The invention may best be understood with reference to the accompanying drawings wherein illustrative embodiments are shown.